Rational synthesis of 3D coral-like ZnCoO nanoclusters with abundant oxygen vacancies for high-performance supercapacitors.

Transition metal oxides with high theoretical capacitance are regarded as desired electrode materials for supercapacitors, however, the poor conductivity and sluggish charge transfer kinetics constrain their electrochemical performance. The three-dimensional (3D) coral-like ZnCoO nanomaterials with abundant oxygen vacancies were synthesized through a facile hydrothermal method and chemical reduction approach. The introduced oxygen vacancies can provide more active sites and lower the energy barrier, thereby facilitating the kinetics of surface reactions.

Facile synthesis of morphology-controlled hybrid structure of ZnCoO nanosheets and nanowires for high-performance asymmetric supercapacitors.

Controllable synthesis of electrode materials with desirable morphology and size is of significant importance and challenging for high-performance supercapacitors. Herein, we propose an efficient hydrothermal approach to controllable synthesis of hierarchical porous three-dimensional (3D) ZnCoO composite films directly on Ni foam substrates. The composite films consisted of two-dimensional (2D) nanosheets array anchored with one-dimensional (1D) nanowires.

Tuning oxygen-containing functional groups of graphene for supercapacitors with high stability.

To investigate the relationship between the oxygen-containing functional groups of graphene and the stability of supercapacitors, reduced graphene oxide (rGO) containing different oxygenic functional groups was prepared by varying the reduction time of GO using hydrazine as the reducing agent. TEM, XRD, Raman, and XPS characterizations revealed that, as the reduction time increased, the sp structure in the rGO sheet was restored and the obtained rGO had good crystallinity accompanied by removal of the oxygenic functional groups. The analysis of the content of the different functional groups also suggested that the reduction rate of the oxygenic functional group was C-O > C[double bond, length as m-dash]O > O-C[double bond, length as m-dash]O.

Effects of low work-function lanthanum oxides on stable electron field emissions from nanoscale emitters.

Nanoscale electron field emitters are known to produce more stable electron emissions than conventional emitters. This has been attributed to size effects; nanoscale emitters can operate with a small emission current and a low extraction voltage, which reduces the bombardment of residual gas ions on the emitter tip. However, our experiments discovered that nanoscale LaB emitters had extremely stable emissions, suggesting that chemical effects are present in addition to size effects.

Effect of porous structural properties on lithium-ion and sodium-ion storage: illustrated by the example of a micro-mesoporous graphene (MoS) anode.

In this work, we synthesized micro-mesoporous graphene (MoS) with different compositional ratios co-reduction of graphite oxide and exfoliated MoS platelets. We systematically studied the performance of the micro-mesoporous graphene (MoS) as anodes in lithium-ion batteries and sodium-ion batteries. The results show that the specific surface areas of the composites decrease with introducing MoS.

Facile preparation of flexible binder-free graphene electrodes for high-performance supercapacitors.

A facile two-step strategy to prepare flexible graphene electrodes has been developed for supercapacitors using thermal reduction of graphene oxide (GO) and thermally reduced graphene oxide (TRGO) composite films. The tunable porous structure of the GO/TRGO film provided channels to release the high pressure generated by CO gas. The graphene electrode obtained from reduced-GO/TRGO (1 : 1 in mass ratio) film showed great flexibility and high film density (0.

A stable LaB nanoneedle field-emission point electron source.

A material with a low work function exhibiting field-emission of electrons has long been sought as an ideal point electron source to generate a coherent electron beam with high brightness, long service life, low energy spread, and especially stable emission current. The quality and performance of the electron source are now becoming limiting factors for further improving the spatial resolution and analytical capabilities of the electron microscope. While tungsten (W) is still the only material of choice as a practically usable field emission filament since it was identified more than six decades ago, its electron optical performance remains unsatisfactory, especially the poor emission stability (>5% per hour), rapid current decay (20% in 10 hours), and relatively large energy spread (0.